Prepared under direction of the Chief of Ordnance Paragraph Section I. General. Purpose 1 Scope 2 References 3 Data 4 Description 5 Operation 6 II. Disassembly, assembly, and head space. General 7 Removal of groups from gun 8 Replacing groups in gun 9 Head space 10 Detailed disassembling 11 Assembling 12 Changing from left-hand feed to right-hand feed 13 Converting a fixed gun into a flexible gun 14 III. Stoppages and immediate action. Stoppages 15 Immediate action 16 IV. Care and preservation. General 17 Points to be observed before a flight 18 Points to be observed after a flight 19 Working in the machine gun 20 Care and cleaning of gun 21 Method of filling oil buffer 22 V. Ammunition. Nomenclature 23 Classification 24 Identification 24 Model 26 Lot number 27 Section V. Ammunition — Continued. Paragraph Identification card 28 Grade 29 Marking 30 Care, handling, and preservation 31 Storage 32 Authorized rounds 33 Ballistic data 34 Defects found after firing 35 Field reports of accidents 36 VI. Spare parts and accessories. Spare parts 37 Accessories 38 Page Appendix.- List of references 51